Affiliation: | (1) Istituto Nazionale per la Ricerca sul Cancro, 16132 Genoa, and AVIS, Bergamo, Italy;(2) New York State Department of Health, Roswell Park Memorial Institute, 14263 Buffalo, New York;(3) Istituto di Biologica Cellulare, C. N. R. 00196 Rome, Italy;(4) Roswell Park Memorial Institute, 666 Elm Street, 14263 Buffalo, New York |